The present invention relates to a silver halide emulsion and the like and, more particularly, to a silver halide emulsion and the like characterized by a silver halide grain chemical sensitization method.
To improve the graininess of images of color photosensitive materials, particularly color reversal sensitive materials often used by professional photographers, it is necessary to minimize the size of emulsion grains contained in each color sensitive layer. However, the sensitivity generally lowers when the grain size is decreased, so a sensitivity increasing technique is required to compensate for this lowering of the sensitivity. U.S. Pat. Nos. (hereinafter also referred to as U.S.) 4,434,226, 4,439,520, 4,414,310, 4,433,048, 4,414,306, and 4,459,353 have disclosed sensitivity increasing techniques by which the color sensitization ratio by spectral sensitization dyes is improved by increasing the surface area of grains for receiving light by the use of tabular silver halide grains, compared to a case wherein grains of the same size are used. The present inventors have examined grains having an aspect ratio of 2 or more and found that as the aspect ratio is increased, it is possible to use larger amounts of sensitizing dyes and improve the spectral sensitivity.